1. Field of the Invention
The present invention relates to an apparatus for measuring alignment which is mainly applicable to a rear suspension of a motor vehicle, and relates to a method of inspecting a suspension by using this apparatus for measuring alignment.
2. Description of the Related Art
As this kind of apparatus for measuring alignment, there has hitherto been known one in Japanese Published Examined Patent Application No. 61888/1991. Namely, the apparatus for measuring alignment comprises: jig means for supporting a suspension sub-assembly, which is made up by assembling a suspension on a sub-frame, in a predetermined position; a supporting frame which is disposed on a side of the jig means; a measuring element which can perpendicularly abut with (or contact) a reference surface which crosses at right angles an axle of a wheel mounting member to be rotatably supported by a knuckle of the suspension; a holding means which can hold the wheel mounting member in a condition to diametrically align the wheel mounting member; a measuring head for supporting the measuring element so as to be inclinable about a longitudinal camber axis and about a vertical toe axis, the measuring head having camber detecting means and toe detecting means, the camber detecting means being for detecting an angle of inclination of the measuring element about the camber axis, the toe detecting means being for detecting an angle of inclination of the measuring element about the toe axis. The measuring head is supported by a pushing means so as to be pushed (or urged) laterally inward so that the measuring element can come into abutment with the reference surface of the wheel mounting member.
In this conventional apparatus, the holding means is constituted by a plurality of holding pieces which are mounted on the measuring element so as to be opened and closed. The measuring head is pushed laterally inward to thereby bring the measuring element into abutment with the reference surface of the wheel mounting member, and also the holding pieces are closed to thereby hold the circumferential (or peripheral) surface of the wheel mounting member. According to this arrangement, the measuring element becomes capable of inclining about an axis of camber depending on the change in camber by means of the member for adjusting the alignment of the suspension. It thus becomes possible to adjust the alignment while measuring the camber.
In the above apparatus as described in the Japanese Published Examined Patent Application No. 61888/1991, the toe is not measured. However, by supporting the measuring element so as to be inclined about the vertical toe axis and by mounting, on the measuring head, a detecting means which measures the angle of inclination about the toe axis, the toe can also be measured.
When the wheel mounting member is held by the holding means, the camber and the toe are not fixed because the alignment has not been made yet. As a result, in some cases, the wheel mounting member is held while the axis of the wheel mounting member, i.e., the wheel axle is inclined, relative to the holding center of the holding means. If the holding means is mounted on the measuring element as in the above-described conventional apparatus, the center line of the measuring element becomes the center of holding. Therefore, if the wheel mounting member is held in a state in which the wheel axle is inclined relative to the holding center, the measuring element will no longer abut at right angles with the reference surface of the wheel mounting member. The camber and the toe therefore can no longer be accurately measured.
In view of the above-described points, the present invention has a first object of providing an apparatus for measuring alignment which can surely abut the measuring element with the reference surface of the wheel mounting member so that the camber and the toe can be accurately measured.
Further, generally speaking, the suspension has the following arrangement. Namely, a predetermined one arm out of a plurality of arms is connected, via an adjustment member such as an eccentric cam, or the like, to the sub-frame such that the position thereof can be adjusted. The alignment can thus be adjusted by the adjusting member. After the alignment has been adjusted at the stage of sub-assembling of the suspension, the suspension is mounted on the vehicle body.
Recently, a multi-link type of suspension comes to be used as the rear suspension of the motor vehicle. The multi-link type of suspension is made by constituting an upper arm and a lower arm of a double wishbone type respectively by a plurality of links. The alignment is made adjustable by adjusting the position of connection of a predetermined one link relative to the sub-frame.
Even if the suspension constituting members which are connected to the sub-frame in an unadjustable manner are deviated in its connecting position from the reference position, the alignment can be adjusted by the adjustment of the connecting position of that suspension constituting member relative to the sub-frame which is connected to the sub-frame via the adjustment member, thereby obtaining the required toe and camber.
However, in order to make the suspension in a high quality, it is necessary to remove the assembly error of the suspension such as the deviation in the connecting position of the suspension constituting members relative to the sub-frame. In this case, it may be possible to control the assembly accuracy by measuring the position of each of the connecting positions. This is however time-consuming.
In view of the above points, the present invention has a second object of providing a method of inspecting a suspension in which the assembly accuracy of the suspension can be easily discriminated.